The problem which the present invention addresses relates to a flexible spindle which is suitable for transmitting a torque without undergoing any deformations in radial or longitudinal direction owing to the effect of the stresses deriving from the simultaneous application of said torque and an axial pull or compression force to it.
At present flexible sheaths exist like, e.g., the one which is disclosed in the German Patent Publication No. 4,208,221, which is used as catheter for transmitting relatively low radial and axial forces. This document further discloses spirals of different length, whereby less spirals are used in order to facilitate sharp bending of the catheter. The flexible spindle consists of coaxial helical spirals each having a winding direction opposite to the winding direction of the adjacent spiral.
U.S. Pat. No. 3,435,905 discloses further an angle drive tool for transmitting a torque but no axial forces. The flexible sleeve consists of a pair of helical springs which are coaxially telescoped and oppositely wound.
Starting from this prior art it is the object of the present invention to provide for a flexible spindle which is capable of transmitting both radial and axial forces without deformation of the spindle, with small loss of the force applied.